In 1978, I visited my first war zone, Beirut. There were, in fact, several wars going on. The Israelis had made an incursion in the south, but there was chaos everywhere, with various local militias squaring off in the streets. Two of them had battled each other for control of the Holiday Inn. Imagine that. Beirut, clearly, had been a civilized and sophisticated city; parts of it still were — and yet it was descending into the unthinkable. The lesson was stark: My American soul, my life experience, had assumed that civilization was a rock-solid given, especially in historic cultural...